Airplane wing with boundary layer control



June 7, 1960 H. coANDA AIRPLANE -wING WITH BOUNDARY LAYER CONTROL 2 Sheets-Sheet 1 Filed Feb. 6, 1958 June 7, 1960 H. COANDA AIRPLANE WING WITH BOUNDARY LAYER CONTROL 2 Sheets-Sheet 2 Filed Feb. 6, 1958 Atf, least one staticblower;

gasieniergesi'from said lo said dishargedgasfintoi United States Patent O l l n y 2,939,650 n e AIAIRPLArui wlNG WITH BOUNDARY e LAYER CONTRoL vI-Ieuri Coau'da,fParis,France, assigilor toSebac Nouvelle v, S.A.,`Suisse,Frauce,acorporatiou of'Franceji Filed Feb. 6, 195s, ser. No. 713,620 Claims priq'rify, application France Feb. y7, 1957 4 Claims.V (C1. z44--4z) .The present inventionk concerns .airplane wings of all types, and in particularwings which vreduce head resistance and increase lift bythe use of gas under pressure, which'is 'discharged through slots pierced in the said A vprincipal object of the present'invention is to imr' *ce 2,939,650

.liefsnfsd Jane 7.,1969

,Figi 1 is aplan View (from above), with apart/of the extados, removed, of part'of a` wing in accordancelwith the inventioniff.. .Y Y., y v 'LFig. YZvis a vSection through II-f-II of Fig. 1; f H i 3 represents on ralarger scale the detailfof aportiou of the blower ,shown in Fig. 2;

I @Fig. 4showsanqthe detail ofFiganiisbeinginespan;

provethe aerodynamicfcharacteristics of an airplane wing, ,y 1

increasing its lift to the maximum and reducing its dragl as much aspossible, as a-result of an improvedwing design. It has' already been proposed' that the' aerodynamic characteristics of a wing should be improved or itspropulsion obtained by blowingiair over the wing (air-swept wing), achieving fair eicieucy 'in Vthe vuse of energy to compress this air. y v

Thepresent invention aims at obtaining,in an airswept wing, increased eciencyinthe/expenditure of energy for compressing a fluid, rsuch as' air, by the vconstruction of a lwing withV superior aerodynamic characteristics.` Y

the air around the wing'is obtainedby lcausing a How of gas to produce siirlultaneous'ly:V

l .(1) A vdischarge of gasV through slots which are genj erallyr spanwise (inrelation to the wing) vandY Y j (2)-An' intakeff surrounding aii'fby suction through certain areas of theextrados-ofthe wing.

, The particulars vof a'wing inI accordance with Ithe inven- Y tion vare asfollows' Y A system for` the distribution of a compressed gas, such as compressed air, equipped with aty least one `'static lblower which sucks in the'surrounding i A' collector to receive. the gas discharged by the one or morestaticblowersgf Y 4 Conduits forconveymgat least la 'part ofsaid dischargedjgas to anapproximately spanwise slot situated onth'e extradosvfofthefjwing, roughly at thegpoint of thickness of the`wiiig, thisslot `is characterised by'th'erffact thatits rear'lip tco'nsiderfedfwhen thefwingb is 4that its extension ,10am whi hthei And/or'gconduitsio co eying atleast foftheA For a better understanding of theinyention, one particular application by way of example (non-restrictive) In accordancewith theinvention, a hypercircula'tion Vof Y n l to gases Vin the Vpartof the extrados next to the leading edgeand/or. the part of the Y rextrades next .to ther/trailinged'geg' wisefslot runninggalongthe extrados at the thickest part ofthewing; Fig. .5-nal1y', lshowson a larger scale thanin Fig. 2,l anotherposs'ible position of thefflap at the trailing edge ofthe wing. y.

Auid "such ascornpressed air, coming from a cornpres's'or,` not shown in the drawing, which may beof any typesandmounted sin the fuselage, arrives throughvk a channel 1 running longitudinally, and is distributed through pairs of transverse conduits 2 to a collector ring 3, there being onepair of ycollectors 3 for each static blower 4.-..1In actual fact, a Wing usually contains a series of static blowers 4. Y r

EachV blower 4 represents a body of revolution about an axis, A-AA and includes: Firstly, two .toric chambers 5 fed Awith uid under pressure coming hom the collectors 3 through small pipes 6` and; .discharging this uid under pressure through the y annular slotsf?y into"`v the` space Sicontained between the inside kwalls 9 offthe chamber 5, facingtowards the axis 5l-A, and av central piece10;

vSecondly,an intermediate, conduit space 11 for expansion Vand compression, of, the iluid from space 8. The sectionroffmeansll in a radial half-plane containing A--A is thatV of a -convergent-divergent nozzle Vor Venturi, whichleadsinto an annular chamber or collector 12. Itmay be seen from Fig. 3` that the slot 7, 'whose opening an'beadjustedfbymoving in relation to each other the walls 9.12v and 9a of the chamber 5, is designed to bring into play the physical phenomenon known in`professional circlesas. the ,Coanda Effect? (deiinedbelow),V l

Foi-this reason,-the wall 9, whichj forms` the extension of oneeofthe lips 13 of the Ymouth ofthe slot 7, progressively vdiverges.; from the axis of the exit,14 ofthe. slot '7 (in aradial half-plane containing A-A)y thus the wall v9 consists vof facets (in the said Vradial half-plane) form- `ingsuccessivelygreater'angles with the axis 14. a 4 Itis known that when the extension of one lip ofthe l n ipgifuainai Chamber situated vnext to'the'trailingedge,of` the wing and' partially closedl tlirou'ghjthet s lot adheres to this extended lip, creating a pressuredrop orpartialvacuum, and consequently asuekvtionefrfect ont the surrounding gasv (or fluid): this is the --phenomenor-'which 'constitutes-theCoandaEffectf 1 .'Thefsp'ace .8 communicates witlr the hollow interioriof" the wingand,i when; the Coanda -Eifect isV .brought into play, air is sucked'` in asshown'by-the arrows V15. Y v i-,In :accordance with an essential characteristic Vofthe pinvention, the interior of the wing communicates. with vthefioutside atmosphere :throughaV series of" aperturesv or holszpiercedgon the one hand, in the rear part of the Awing upper'suvrfaces (area 16), and on the other hand in that :portion of the upper or top surfaces of the wing lyingxjstbehid the leading vedge (area 18). vThe pressure ldrop created inthe interior of 'the' wing'caupses su'ction of .the outside air through the holes in areas 16 and V1,8v (shown by arrowsl19 and 20 respectively).

, yThe result isfthatQthejcornpressedairV emergingY from the slots7 sucks inthe lboundary layer' in areas 16 and18 nand,theawhole` Qf/,th'egaseous mass-(compres`sed airY 'in the annexed drawings, in which: Y

.emerging from the 4slots 1 and airsucke'd inV from outside through the rieles; aeasgis and is, as vasresult of the Coanda Effect)v passes through the distributors llrinto the collectors 12. The collectors 12 communicate on the one hand, by a series of short conduits 21, with a longitudinal chamber 22, situated just under the wall of the extrados 34, and on the other hand, by aseries of short conduits 23, with a longitudinal chamber 24 of .reilghly circular section, situated near the trailing edge 36, v

The chamber. 22. opens into the surrounding air'through a longitudinal slot 2S which brings into play the Coanda Effect, since one of its 'lips is extended (Wall Z6) and progressively diverges from the axial plane 27 in which the compressed air emerges under pressure fromthe slot 25.Y The result is a marked reduction in pressure on the extrados, which contributes to the wings liftand exerts suction on` the air in front of the leading'edge, thus diminishing the drag.

l In the chamber 2.4 is mounted a longitudinal. bar 31, roughly cylindrical but extended by a trailing edge 32 which, together with the bar, forms a flap. Between the bar 31 and ythe truncated .rear portion 30 of the wing, there remain longitudinal passages 28 Vand 2,9.

Y On its upper part, the bar 31 comprises, first, a series of channels 37 running between a longitudinal wall 38 and the Vbar 31, partitions 39 being provided at intervals to connect the wall 33 to the bar 31, and secondly, a 1ongitudinal recess or groove 40. f y .Y

In the same way, the barv31 comprises on its lower part, vfirst, a Vseries of channels 37 running between a 1ongitudinal wall 3SV and the bar 31, partitions 3,9' being provided at intervals to connect the wall 138 to the bar 31, and secondly, a longitudinal recess or groove 40', The effect of the grooves 401 and (40' is to Vcause additional suction on thesurrounding air by the compressed fluid emerging from the channels 37 `and 37". Y

lThe flap 31, 32 can be made to turn on its horizontal axis Vof revolution 41 which may coincide with the axis 33 of the cylinder 31 but should preferably be setb'off from it in such a way that passages 28 and 29 are modified during rotation of the bar 31, it being even possible for the wall 38 or 38 to reach a point where it touches the internal surface of the chamber 24. j

In Fig. 2, the circulation of the gas has been indicated by arrows and the imaginary extensions of the extradosf34 and the intrados 35 which end at the imaginary trailing edge 36 of the non-truncated wing have been shown in broken lines, the flap 31-32 being shown in its -normal position, whereask the .position of the flap'Sl-SZl represented in Fig. k corresponds to increased lift'for the airplane comprising the wing `herein described and reprev sented.

YAround this wing there is therefore a hypercirculation of air, for the compressed air, arriving Vthrough theconduit 1, vcauses in each static blower 4 an intake ofadditional air which is sucked Yfrom the boundary layer on the extrados through the permeable areas 16Sand 1-8, andthe total mass fof air delivered by veach unit 4 (compressed air from the conduit `1 plus the air sucked in.);is discharged into the outside air, Von one hand'through the' slot 25', creating'a reduced pressure above the "extrados, and on the other hand rthrough' the channels37 `andiW, producing a propelling thrust v and/or increased or decreased lift.

The whole system contains nopar'twhatevery in rota'- tional or alternating motion, so that it creates no vibration whatsoever in the wing.

Various alterations, improvements or additions can of course be made to the application described and represented without constituting any departure from thescope of the invention. Y

For example, in one variation, the collector 12 could consist of a helicoidal chamber, in which case area 11 would be equipped with fins in orderto` give the gas ay What 1 claim is:

1. 1n an aircraft Wing comprising, an elongated main body provided with at least an air-intake section having an air-pervious area extending spanwise on the wing adjacent a leading edge thereof and an air-pervious upper surface extending spanwise adjacent a trailing end of the wing'body, a flap extending along said trailing end and having surfaces converging to form the trailing edge of the wing, means pivotally mounting the flap on said main body, blower means interiorly of the wing body having means in communication with said air-pervious upper surface defining jointly with said flap air-blast slots eX- tending spanwise and in communication with the body interiorto How air over the converging surfaces of the iap in a direction toward said trailing edge, means cooperative with said blower means for taking a suction interiorly of the wing body, the upper surface of said wing having a slot extending spanvw'se for blowing air over the surface of the wing, said last-mentioned slot being disposed in a forward part of said wing, closer to the leading edge than to the trailing edge, and having in a crosssection of the Wing anextended lip which continually recedes from the direction of emergence of air through said'slot for flowing air .over the .upper surface of the wing in a direction toward the trailing edge and means providing communication between the last-mentioned slot and said blower means for providing air under pressure .to said slot to cause'the air under pressure to fiow out ofthe last-mentioned slot and over the upper surface of the wing body Vtoward the trailing edge.

2. In an aircraft wing comprising, an elongated main body provided with at least an air-intake section having an air-pervious areaV extending spanwise on the wing adjacent a leading edgethereof and an air-pervious upper surface extending spanwise adjacent a trailing end of the wing body, a flap extending along said trailing end and having surfaces converging to form the trailing edge of the Wing, means pivotally mounting the -iiap on said main body, blower means interiorly of the wing body having means defining a first chamber interiorly of the wing in communication with said air-pervious upper surface, means in communication with said chamber defining jointly with said hap :air-blast slots extending spanwise and in communication vwith `said chamber to ow air over the .converging surfaces ofthe flap ina direction toward said trailing edge, a first venturi nozzle having an inlet en d in communication with the interior ofthe wing body, a convergent portion, a divergent portion for discharging into said rst chamber andV into'saidair-blast slots, a second venturi nozzle having an inlet end incommunication with the interior ofy said wing body, a convergent portion, a divergent portion for discharging into saidljiirst chamber, means defining a second chamber disposed cooperative with said venturi nozzles and havingapair of circular slots each opening into a correspondingy convergent portion'of `said venturi nozzles in-the Vicinity ofthe corrresponding inlet e'nd,.meansv for delivering a gaseous fluid y under pressure into said second chamberto jcauseit to flow out ofY saidcircular slots, saidzcircularvslotshaving in anA vaxial Asection through the -corresponding nozzle an jextendedlip'which continually recedes fromthe directionY said circular slots, the upper surface. of 'said' wingv having Y a slot extending spa-nwise Yfor blowing air ,over the surface of the wing, said last-mentioned'slot being disposed infa forwardpart of said wing closer .to the leading edge than to the trailing edge and having in a cross-.section of the wing an extended lip which continually. recedes from the direction of emergence of air through saidslotfor-owing air over the upper surface of the Wing inea direction toward the trailing edge', .and means providing communica. tion between the Vlast-mentioned slotandthefiirst chamber. p Y

Y 3. In an aircraft wing comprising, an elongated Vmain body provided withV atleast an air-intake, section having having surfaces converging to form the trailing edge of` the wing, means pivotally mounting the flap on said main body, blower means interiorly of the wing body having means defining a rst chamber interiorly of the wing in communication with said air-pervious upper surface, means in communication with said chamber defining jointly with said flap air-blast slots extending spanwise and in communication with said chamber to ilow air over the converging surfaces of the flap in a direction toward said trailing edge, a venturi nozzle having an inlet end in communication with the interior of the wing body, a convergent portion, a divergent portion for discharging into said iirst chamber and into saidair-blast slots, means dening a second chamber disposed cooperative with said venturi nozzle and having a circular slot opening into the convergent portion of said venturi nozzle in the vicinity of the inlet end, means for delivering a gaseous uid under pressure into the last-mentioned chamber to cause it to ow out of said circular slot, said circular slot having in an axial section through the corresponding nozzle an extended lip which continually recedes fromtthe direction of emergence of said compressed gaseous uid through said circular slot, the upper Vsurface of said wing having a slot extending spanwise for blowing air over the surface of the wing, said last-mentioned slot being disposed in a forward part of said wing and having in a cross-section of the wing an extended lip which continually recedes from the direction of emergencefof air through said slot for flowing air over the upper surface of the wing in a direction toward the trailing edge, and means in communication with said -rst chamber for providing gaseous nid underrpressure to the last-mentioned slot. Y

4. In an aircraft wing comprising, van elongated main body provided with at least an air-intake ksection having an air-pervious area extending spanwise on the wing adjacent a leading edge thereof and an air-pervious upper surface extending spanwise adjacent a trailing end of the wing body, a flap extending along said trailing end and having surfaces converging to form the trailing edge of the wing, means pivotally mounting the iiap on said main body, blower means interiorly of the wing body having means dening a rst chamber interiorly of the Wing in communication with said air-pervious upper surface, means in communication with said chamber defining jointly with said ap air-blast slots in communication with said chamber to ow air over the .converging surfaces of the iiap in a direction toward said trailing edge, a venturi nozzle having `an inlet end in communication with the interior of said wing body, a convergent portion, a divergent portion for discharging into said first chamber, means defining a second chamber disposed cooperative with said venturi nozzle and having a circular slot opening into a corresponding convergent portion of said venturi nozzle in the vicinity of the inlet end, means for delivering a gaseous fluid under pressure into the last-mentioned chamber to cause it to flow out of said circular slot, said circular slot having in an axial section through the corresponding nozzle an extended lip which continually recedes from the direction of emergence of said compressed fluid through said circular slot, the upper surface of said wing having a slot extending spanwise for blowing air over the surface of the wing, saidA last-mentioned slot being disposed in a forward part of. said wing closer to the leading edge than to the trailing edge and having in a cross-section of the wing an extended lip which continually recedes from the direction of emergence of air through said slot for flowing air over the upper surface of the wing in a direction toward the trailing edge, andI means providing communication between the last-mentioned slot and the rst chamber.

References Cited inthe file of this patent UNITEDSTATES PATENTS 2,585,676 Poisson-Quinton Feb. l2, 1952 

